Many software development companies are making a profit using the proprietary software model. Why should they release their code as OSS? Eric Raymond has an essay[37] which investigates the financial reasons for going OSS versus staying proprietary. Some common reasons are: make it OSS when it's stopped being competitive (e.g. OpenDX[38]), or when the selling the software is not directly part of your business plan (e.g. when Cisco made major improvements to the Unix printing infrastructure)[37].